Metabolic characteristics of early life history stages of native marble trout (Salmo marmoratus) and introduced brown trout (Salmo trutta) and their hybrids in the Soča River

Abstract

Metabolic potential and respiration rate have been measured in the early life stages of native marble trout Salmo marmoratus (MT), introduced brown trout Salmo trutta (BT) and their hybrids (MH = female of MT 9 male of BT and BH = female of BT 9 male of MT) to examine the differences in their metabolic characteristics. Metabolic potential and respiration rate were lowest in each developmental stage in MT, followed by MH, BT and BH. The ratio between metabolic potential and respiration rate (ETS/R) in larvae was also lowest for MT (1.0) and MH (1.1), followed by BT (1.4) and BH (1.6), indicating more intensive exploitation of metabolic potential for actual respiration in MT (100%) and MH (~90%) than in BT (~70%) and BH (~60%). Lower ETS/R means a disadvantage in the case of enhanced metabolic activity due to insufficient enzyme machinery needed for energy production. Thus, potential and actual metabolic activity and ETS/R ratio could account for the different competitive abilities among pure trout species and their hybrids in a particular environment. This is the first report on biochemical and physiological differences between pure MT and their hybrids. The combination of metabolic and respiration rate measurements appears to be a useful tool for estimating the metabolic properties in the early developmental stages of fish.

Size-age population structure of an endangered and anthropogenically introgressed northern Adriatic population of marble trout (Salmo marmoratus Cuv.): insights for its conservation and sustainable exploitation

“…Subsequent molecular studies confirmed the presence of hybridization between these two species in the wild ( Giuffra, Guyomard & Forneris, 1996 ; Lucarda et al, 2000 ; Zerunian, 2003 ; Jug, Berrebi & Snoj, 2005 ; Turin, Zanetti & Bilò, 2006 ; Lucarda, 2007 ; Meldgaard et al, 2007 ; Meraner et al, 2010 ; Meraner & Gandolfi, 2018 ). It is still unclear whether these hybrids are adaptively advantaged or disadvantaged (positive or negative heterosis, respectively) either in sympatry or allopatry with ‘genetically pure’ marble trout, though possible ecological differences and interactions between genetically discriminated hybrids and ‘pure’ individuals have been explored ( Meldgaard et al, 2007 ; Meraner et al, 2010 ; Simčič, Jesenšek & Brancelj, 2017 ). Several ecological studies, including some early investigations on population density, size-age structure, and fishing pressure, phenotypically discriminated between pure and hybrid individuals within populations, analyzing them separately ( Alessio et al, 1990 ; Jelli & Duchi, 1990 ; Jelli, Alessio & Duchi, 1996 ; Turin, 2000 ).…”

Thermal performance of the electron transport system Complex III in seven Alabama fishes

“…Complex III assays can use tetrazolium dye (reduced to formazan) as the final electron acceptor in place of oxygen. As such, the assay estimates the rate that could be achieved by an organism's energy production pathways by detecting electron transfer activity (Maldonado et al, 2012; Relaxans 1996; Simčič et al, 2017). Initially used to estimate respiration rates in mesopelagic fishes considered too fragile for laboratory acclimation postcollection (Belcher et al, 2020), Complex III activity can estimate potential respiration rate in fishes, estimate growth, and quantify metabolic effects of introgression (Ikeda, 1989; Simčič et al, 2017).…”

“…As such, the assay estimates the rate that could be achieved by an organism's energy production pathways by detecting electron transfer activity (Maldonado et al, 2012; Relaxans 1996; Simčič et al, 2017). Initially used to estimate respiration rates in mesopelagic fishes considered too fragile for laboratory acclimation postcollection (Belcher et al, 2020), Complex III activity can estimate potential respiration rate in fishes, estimate growth, and quantify metabolic effects of introgression (Ikeda, 1989; Simčič et al, 2017). By quantifying enzyme Complex III activity at various temperatures, thermal performance curves can be generated for this complex activity in the electron transport system, which can then be used to quantify temperature effects on an organism's metabolism.…”

“…Assessing enzyme performance at various temperatures is not new; electron transport system (ETS) assays have been used for decades for a variety of organisms ranging from plankton to fish (e.g., Belcher et al, 2020;Gopalan et al, 1996;Ikeda, 1989Ikeda, , 2016Packard et al, 1971;Simčič et al, 2017;St-Pierre et al, 1998). Complex III (ubiquinol cytochrome c reductase) has been identified as a rate-limiting step of OXPHOS (Maldonado 2012).…”

A metabolic syndrome in terrestrial ectotherms with different elevational and distribution patterns

“…For example, seasonal variations in metabolic activity were reported for zooplankton (Simčič and Brancelj 2004) and reptiles (Seebacher et al 2003); metabolic properties of amphipod species were modified when inhabiting contrasting environments, i.e. subterranean vs surface ; metabolic characteristics of freshwater fish were related to their habitat conditions (Simčič et al 2017); and metabolic activity of invasive and native bivalve species differed between two species that varied in competitive ability (Bielen et al 2016). Moreover, many studies exploring metabolic performance or activity indicate the importance of the acclimation of physiological traits to environmental conditions (Pörtner andKnust 2007, Žagar et al 2015a).…”